TLS 1.3 get’s blocked by Cisco, Avast & NSA

The latest TLS 1.3 draft has several issues which needs to be solved – those problems are related to Cisco, Avast and the NSA. The reason why TLS 1.3 isn’t official released are problems – Middleboxes. Devices like some Canon printers or Browsers (like Chrome which supports the latest draft) dropping the TLS connection. The specific reason is unknown but there some trails found, especially on Canon printers which reveals old NSA operations. The developer David Benjamin mentioned such problems now officially.



The so-called next generation Firewall (called Firepower) from Cisco blocks TLS 1.3 by terminating the connection, the Decrypt – Resign functions seems to be broken. Google already informed Cisco about the issue but they haven given any statement (yet).


The Anti-Virus program from Avast has a feature which interjects and inspect TLS traffic, which is done by a local installed Browser certificate. This function is often under criticism because on a local installed AV it makes no sense to install a Browser certificate, the HTTPS traffic could be analyzed afterwards with a Browser extension.

Canon printers and traces of an old NSA operation

MX492, MG3650, MX495 are mostly affected, which means other printers could be also compromised. RSA Security is a Company which is behind all this and they are the ones which coded the BSAFE libraries for the printers. Remeber the Dual EC DRBG scandal? They got over 10 million for the backdoor directly from the NSA.

Canon has mentioned that there planing to roll-out a firmware upgrade to solve it but the trust is anyway long gone after the leak.


  • [TLS] Additional TLS 1.3 results from Chrome (
  • On the Possibility of a Back Door in the NIST SP800-90 Dual Ec Prng (PDF)
  • The trouble with new TLS version numbers (
  • Lucky Thirteen: Breaking the TLS and DTLS Record Protocols (
  • CRIME Attack (


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